Dual purpose dolly for semitrailers



Jan. 14, 1969 s. BARKER ET AL. 3,421,778

DUAL PURPOSE" DOLLY FOR SEMITRAILERS Filed Nov. 18, 1966 Sheet of 4 INVENTORE 57////1/ 5/4/6556 54/2 [456K Jan. 14, 1969 BARKER ET AL -3,4'21,778

DUAL PURPOSE DOLLY FOR SEMITRAILERS Shee t Z 01'4 Filed Nov. 18. 1966.

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Jan. 14, 1969 s, BARKER ET AL DUAL PURPOSE DOLLY FOR SEMITRAILERS Sheet 3 of 4 Filed Nov. 18, 1966 79 Em J5 Jan. 14, 1969 5, BARKER ET AL 3,421,778

DUAL PURPOSE DOLLY FOR SEMITRAILERS Filed Nov. 18, 1966 Sheet 4 of 4 576/2) A/'%5%Z /54% agar United States Patent 2 Claims ABSTRACT OF THE DISCLOSURE A wheeled dolly for use as either an auxiliary wheeled axle for a truck when towing a large semitrailer or as a towing connection between adjacent ends of two smaller semitrailers. The dolly includes a longitudinal frame with a hitch at its forward end for coupling a truck or a semitrailer and a fifth wheel device pivotable about a transverse axis and selectively longitudinally shiftable relative to the dolly frame to automatically engage a resilient snubber device at the rear of the frame for resisting pivotal movement of the fifth wheel device while permitting variation at its angular position.

This invention relates to transportation systems and is particularly directed to improvements in apparatus useful with tractors and semitrailers.

Auxiliary wheeled axles for tractors or trucks are well known, and they serve to provide additional ground wheels for supporting the forward end of a large semitrailer. A device of this type is shown in the Kirksey Patent No. 2,330,897 granted Oct. 5, 1943. Converter dollies are also well known for converting a semitrailer to a full trailer and are commonly used for towing a second semitrailer from a first semitrailer, the first semitrailer being towed by a tractor or truck. An example of such a converter dolly is shown in the Knox Patent No. 2,254,532 granted Sept. 2, 1941.

It is the principal object of the present invention to provide an improved dual purpose device which may be used either as an auxiliary wheeled axle for a truck or tractor, or as a converter dolly for a semitrailer. A dual purpose device of this type permits great flexibility in trucking operations. Thus, the same truck can be used, with the dual purpose device attached to the rear thereof, to pull a single large semitrailer, the weight of the forward end of the large semitrailer being carried on the truck wheels and also on the wheels of the dual purpose device, or the truck may be used to tow semitrailers in tandem, with the dual purpose device serving as a converter dolly for the second semitrailer.

Another object of this invention is to provide such a dual purpose dolly device which may readily be changed from an auxiliary wheeled axle device for a tractor or truck, to a converter dolly for the second of two tandem semitrailers, in a minimum of time and without danger to the operator. A more detailed object is to provide adjustable meanslfor varying the angular position of the fifth-wheel device relative to its supporting frame, so that when the dual purpose dolly is supporting the forward end of a semitrailer the forward end of the frame may be raised or lowered as needed for connection to either the truck or to another semitrailer. Another object is to provide a resilient snubber of novel construction for resisting pivotal movement of the fifth-wheel device on the dolly relative to the frame of the dolly.

These and other objects of the invention are achieved by providing a dual purpose dolly having a longitudinal frame supported by ground wheels turning about a transverse axis. The frame carries a fifth wheel which may be 3,421,778 Patented Jan. 14, 1969 moved forward on the frame for supporting the forward end of a large semitrailer when the dolly is being used as an auxiliary wheeled axle for the truck. The fifth wheel is moved to a rearward position on the frame when the device is being used as a converter dolly for the second of two tandem semitrailers. Adjustable means are provided for varying the angular position of the fifth-wheel device, when in its rearward position, in order to adjust the elevation of the forward end of the frame, while the dual purpose device is supporting the forward end of a semitrailer, thereby permitting the forward end of the frame to be connected either to the fifth wheel of the truck or to the draft hook at the rearward end of another semitrailer.

Other and more detailed advantages and objects will appear hereinafter.

In the drawings:

FIGURES 1 through 8 are side elevations in diagrammatic form, showing how a two-axle truck may be used with a dual purpose dolly of this invention for towing either a large single semitrailer or a pair of smaller semitrailers in tandem. Thus, FIGURE 1 shows the dual purpose dolly serving an an auxiliary wheeled axle for the truck and supporting the forward end of a large single semitrailer. FIGURE 2 shows the truck and dual purpose dolly being moved out from under the forward end of the single large semitrailer. FIGURE 3 shows the truck and dual purpose dolly being positioned under the forward end of a smaller semitrailer. FIGURE 4 shows the truck after being disconnected from the dual purpose dolly. FIGURE 5 shows the smaller semitrailer supported at its forward end by the dual purpose dolly, and shows how the operator may adjust the elevation of the forward extending portion of the frame of the dolly device. FIGURE 6 shows the truck towing the first of two smaller semitrailers and showing the dolly device supporting the forward end of the second semitrailer and connecting the two semitrailers for tandem operation. FIGURE 7 shows the action of the snubber on the dolly device and permitting relative angular movement of the dolly frame and semitrailer when the assembly passes over a high point on the road. FIGURE 8 is a view similar to FIGURE 7 showing the action of the snubber when the assembly passes over a low point on the road.

FIGURE 9 is a side elevation showing a preferred embodiment of this invention and illustrating the dual purpose dolly attached to the truck and serving as an auxiliary wheeled axle therefor.

FIGURE 10 is an end elevation of the device shown in FIGURE 9.

FIGURE 11 is a top plan view of the device shown in FIGURE 9.

FIGURE 12 is a transverse sectional view taken substantially on the lines 1212 as shown in FIGURE 9.

FIGURE 13 is a side elevation partly broken away showing the snubber which connects the frame of the dolly to the fifth wheel on the dolly, when the latter is in its rearward position.

FIGURE 14 is sectional plan view taken substantially on the lines 1 414 as shown in FIGURE 13.

FIGURE 15 is a sectional view taken substantially on the lines 15-15 as shown in FIGURE 13.

FIGURE 16 is a view similar to FIGURE 15 but showing the snubber parts in a different position.

FIGURE 17 is a perspective view, partly broken away, showing a portion of the device of FIGURE 13.

FIGURE 18 is an exploded view of the remaining parts of FIGURE 13.

FIGURE 19 is an enlarged section detail showing a portion of FIGURE 15.

FIGURE 20 is a side elevation in diagrammatic form "ice showing movement of the dolly device toward position under a semitrailer.

FIGURE 21 is a view similar to FIGURE 20 and showing the action of the snubber in lifting the forward end of the semitrailer.

FIGURE 22 is a side elevation in diagrammatic form showing a modification.

Referring to the drawings, the tractor or truck generally designated and shown in diagrammatic form in FIGURES l8 of the drawings, has a frame 11, front wheels 12 which steer, and rear wheels 13 through which tractive power is applied. The frame 11 supports the conventional fifth-wheel assembly 14 (FIGURE 4). Two types of semitrailers are shown. The first type is a conventional large semitrailer 15 having a pair of wheeled axles 16 and 17 at its rearward end and having a conventional kingpin 18 (FIGURE 2) under its forward end. The second type comprises smaller semitrailers 20 and 21, which may be duplicates, and have only one rear axle assembly 22, 23, and are adapted to be towed in tandem, as shown in FIGURE 6. The forward semitrailer 20 is connected to the fifth wheel 14 of the truck 10, and the second semitrailer 21 has its forward end supported by the dual purpose dolly device generally designated 25, which device also serves to provide a towing connection from the conventional hook 26 on the rearward end of the semitrailer 20.

In FIGURE 1, the dual purpose device serves as an auxiliary wheeled axle for the truck 10, and in FIGURE 6 the device 25 serves as a converter dolly for the second semitrailer 21 connected in tandem to the first semi trailer 20.

As best shown in FIGURES 9-12, the dual purpose dolly device 25 has a longitudinally extending frame 30 which includes a pair of parallel side rails 31 and 32 carried on side wheels 33 and 34 rotatable about a transverse axis. The frame 30 is supported on the side wheels 34 and this construction may take the form disclosed in the Barker Patent No. 2,995,383. Near its forward end the frame 30 is provided with a kingpin 35 which is gripped by a locking device in the conventional fifth wheel 14 mounted on the truck 10. Means are provided for preventing lateral swinging movement of the dual purpose dolly 25 with respect to the truck frame 11, and as shown in the drawings, this means includes the rearward projection 37 bolted or otherwise attached to the rear cross member of the truck frame, and a cooperating channel 39 provided on the dolly frame 30 and having a central slot 40 for sliding reception of the projection 37.

Within the rails 31 and 32 there is provided a longitudinal track or guideway 42 for reception of a sliding support 43. A latch (not shown) is provided for securing the sliding support 43 in any one of a series of positions along the length of the track 42. Coaxial transverse pins 45 on the sliding support 43 pivotally support the fifth wheel 47. This fifth wheel 47 on the dual purpose dolly device 25 is similar to the fifth wheel 14 on the truck 10 except that it is adjustable longitudinally of the dolly frame 30, and further, that it is provided with a hook 48 on its under surface. The kingpin 18 on the single large semitrailer 15, or the kingpin 24 on the smaller semitrailer 20 may each enter the slot in the fifth wheel 47 and be latched in position by conventional means. When the forward end of the single large semitrailer 15 is to be carried on the fifth wheel 47, the latter is moved to its forward position relative to the truck frame 11 by sliding the support 43 to the forward end of its travel along the track or guideway 42, and then latched in position. When the forward end of the smaller semitrailer 20 is to be supported on the fifth wheel 47, the latter is moved to the rearward end of the guideway or track 42, and in this latter position the hook 48 engages the crosspin 49 at one end of the snubber device, generally designated 50. The rearward position of the fifth wheel 47 is shown in phantom lines in FIGURE 9.

The snubber or stabilizer 50, best shown in FIGURES 13-19, acts through the crosspin 49 and hook 48 to afford a means of adjusting the relative angular position of the fifth wheel 47 and the dolly frame 30, as well as to provide resilient means resisting such relative movement above and below the adjusted position. The shell 52 is provided with lateral flanges 53 bolted to the frame 30 of the dual purpose dolly. The shell 52 has aligned notches 54 and 55 provided in its front and rear Walls, respectively, for clearance with the hook 48 fixed to the underside of the pivoted fifth wheel 47. Guide shoes 56 are mounted on the upper open end of the shell 52 and provide sliding surfaces for contact with the movable plunger 57 mounted within the shell 52. The upper projecting end of the plunger 57 carries the crosspin 49. The cross-sectional shape of the plunger is similar to the cross-sectional shape of the interior of the shell. The lower end of the plunger 57 is enlarged at 58 for slidable reception in sliding contact with the inner Walls of the shell 52.

Means are provided for moving the plunger 57 lengthwise within the interior of the shell 52, and, as shown in the drawings, this means includes a screw 60 projecting upward into the shell and plunger and engaged by a tubular nut 61 having an internally threaded portion 62 near its lower end. The tubular nut 61 may move axially within the interior of the plunger 57 but is prevented from turning therein by the noncircular flange 63 on the nut which slidably engages a noncircular bore within the plunger 57. A threaded abutment flange 64 is mounted on the lower exterior portion of the tubular nut 61. Positioned between the flange 63 and abutment 64 on the outersurface of the nut 61 is a snubbing assembly, generally designated 65, which includes a pair of noncircular metal washers 66 and a plurality of resilient blocks 68. Another metal washer 67 having a circular aperture is positioned between the lower washer 66 .and the abutment flange 64. Each of the blocks 68 is formed of elastomeric material such as rubber, and each has a central opening for reception of the tubular nut 61. Each block is concave on its outer surface, and each is received within the inner wall 70 of the plunger 57. Opposite ends of this wall 70 terminate in inwardly extending abutments 71 and 72 on the plunger 57. For purposes of assembly, the abutment 72 is provided by bars 74 which slide through aligned apertures 75 in the enlarged portion 58 of the plunger 57.

The screw 60 extends into the gear chamber 77 at the lower end of the shell 52, and bevel gears 78 and 79 are provided for turning the screw .60 in either direction by means of the shaft 80 and coupling 81. The shaft 80 may be turned manually by means of a hand crank 82 (FIG- URE l1) acting through a reduction gear assembly 83 and coupling 84. The hand crank 82 is placed at a location readily accessible to the operator.

From this description it will be understood that rotation of the hand crank 82 is effective to turn the screw 60 within the tubular nut 61, causing the latter to move longitudinally within the shell 52, thereby raising or lowering the crosspin 49. When the hook 48 is engaged with the crosspin 49, the projection and retraction of the crosspin 49 through operation of the crank 82 is effective to shift the relative angular position of the fifth wheel 47 with respect to the dolly frame 30. Moreover, since the snubber assembly 55 including the rubber blocks 68 is operatively interposed between the nut 61 and the plunger 57, forces transmitted through the crosspin 49 in either direction are resiliently opposed by the rubber blocks. When the forces are suflicient to deform all of the rubber blocks so that they totally fill the available space between the nut 61 and the inside wall of the plunger 57, the connection becomes solid without further appreciable resilient deformation.

When the forward end of the semitrailer 2.1 rests on the dual purpose dolly 25, as shown in FIGURE 5, the support is a stable one because the fifth-wheel kingpin 24 is usually positioned slightly forward of the axis of the dolly wheels 33 and 34. By turning the crank 82, the operator may raise or lower the forward portion of the frame 30 of the dolly 25 so that the eye 27 at the forward end of the frame 30 can be positioned at the proper height to engage the draft hook 26 at the rear of the semitrailer 20, or so that the forward end of the frame 30 can be positioned to effect engagement of the kingpin 35 with the fifth wheel 14 on the truck 10. The relative angular position of the fifth wheel 47 and dolly frame 30 are not rigidly fixed, however, since the resilient movement afforded by the snubbing assembly 65 including the rubber blocks 68 permits limited relative angular movement in either direction from the adjusted position. This movement is necessary to permit the assembly to move over a raised portion on the roadway, as shown in FIGURE 7, or to move through a depressed portion of the roadway, as shown in FIGURE 8.

When the dual purpose dolly 25 is being installed in position under the forward end of the semitrailer 21, as shown diagrammatically in FIGURES 20 and 21, the snubber device 50 acts as a bumper or energy storage device. When the rearward surface 85 of the fifth wheel 47 strikes the forward lower corner 86 of the semitrailer, the snubber device 50 absorbs some of the shock and subsequently releases the energy which helps in the lifting of the semitrailer off its landing gear 87 and therefore makes coupling smoother.

A spare tire and wheel 88 may be supported on the dolly frame 30 by means of a bracket 89. The position of this spare tire and wheel serves to balance the forward projecting portion of the dolly frame 30 about the transverse axis of the wheels 33 and 34. Because of this balance the rather heavy device may readily be manipulated and rolled about by a single operator who grasps the eye 27. However, in the event that the truck operator should not require the provision of a spare wheel and tire on the dolly 25, a movable support leg 90 may be mounted on the dolly frame 30a as shown in FIGURE 22. This support leg may carry a castor wheel 91 at its projecting end and may be raised and lowered by means of a crank arm 92 operated by a nut cooperating with a screw 93 turned by means of the crank handle 94. In other respects the dolly device shown in FIGURE 22 is similar to that previously described.

We claim:

1. For use with a truck in towing either a single large semitrailer or two smaller semitrailers, a dolly adapted to serve as either an auxiliary wheeled axle for the truck when towing the large semitrailer or as a towing connection 'between adjacent ends of the two smaller semitrailers, the dolly comprising, in combination: a frame extending longitudinally in the direction of travel, side wheels rotatable about a transverse axis, means supporting the frame on the side wheels, a fifth-wheel device for detachable connection with an element of a semitrailer, support means movable longitudinally on the frame, means pivotally connecting said fifth-wheel device to said support means for pivotal movement about a transverse axis, the frame having a forward portion provided with means for establishing a towing connection with the truck or with one of the smaller semitrailers, adjustable means for varying the relative angular position of the fifth-wheel device relative to said frame when said support means is in a rearward position on said frame, said adjustable means including a resilient snubber, and means for automatically engaging said resilient snubber with said support means upon movement of the latter to its rearward position on said frame.

2. A dolly for use with a semitrailer, having in combination: a frame supported on coaxial side wheels, a fifth-wheel device for detachable connection to an element of the semitrailer, means on said frame supporting said fifth-wheel device for pivotal movement about an axis parallel to the axis of said Wheels, a shell fixed to the frame, a resilient snubber device including a plunger guided for endwise movement relative to the frame, adjustable means including a screw and a nut for moving the plunger, said means including resilient means comprising a plurality of elastomeric elements within the shell and operatively interposed between the nut and the plunger, and means connecting said plunger to said fifthwheel device, whereby said fifth-wheel device may have restricted pivotal movement relative to the frame from an adjusted angular position.

References Cited UNITED STATES PATENTS 2,330,897 10/1943 Kirksey 280-432 2,391,372 12/1945 Weigand 280--438 2,727,755 12/ 1955 Hume 280-438 2,809,851 10/1957 Beck 280-438 2,847,230 8/1958 Hendrickson et a1. 280-438 X 2,978,259 4/ 1961 Buisson 280-438 X 3,203,711 8/1965 Chew 280-423 3,246,912 4/1966 Cunha 280407 3,312,479 4/ 1967 Cunha 280-415 LEO FRIAGLIA, Primary Examiner.

U.S. Cl. X.R. 

